Born in Saint-Amant-de-Boixe, France, on March 24, 1862, Émile Marchoux graduated medical school in Paris in 1887 and specialized in microbiology at the Pasteur Institute. In the early days of his career, he worked as a navy doctor in Benin (then Dahomey) and next as a colonial physician in Indochina and Senegal. During this period, he wrote an influential monograph on malaria. In 1895, under the leadership of Émile Roux at the Pasteur Institute, he developed the world’s first serum with antimicrobial properties, against anthrax. He spent 1901 to 1905 in Brazil studying yellow fever, in the company of Paul-Louis Simond and Alexandre Salimbeni. Working with Salimbeni, he also researched avian spirochaetosis and described its means of transmission. Marchoux headed the tropical microbiology section at the Pasteur Institute and was one of the founders of France’s Society of Exotic Pathology. He is especially remembered for his work on the prevention and treatment of Hansen’s disease. He died in Paris on August 19, 1943.